In order for a printing device to be able to be shared by a plurality of client devices a server device, such as a print server, is normally provided. A print order generated by a client device would be initially transmitted to the print server. The print server stores the print order, i.e. the printing data. In general a queue is provided in the print server in order to manage the execution of the print orders in a specifiable order. When the printing device is available for the print order from the client device, the print server transmits the respective print order for printing to the printing device.
Corresponding network systems and methods for operating the network systems are known from the prior art. However, they suffer from the disadvantage of increased requirements for resources and maintenance. Not only is there a need for an additional server device with corresponding computing and storage performance, but the additional server device also requires maintenance which means additional costs.
A solution to the problem is offered in the U.S. Pat. No. 6,115,132 A which offers a method for operating a network system with a plurality of client devices, at least one printing device in the form of a printer and a print server. The print server, in particular, is used for managing the sequence of the print orders, wherein the print orders as such remain on the client device. After the client device has transmitted printing information, but not the actual printing data, to the print server, this then controls the sequence of the print orders to be executed by the printing device. To this end the print server actively transmits an enable signal to the client device when the printer is ready for printing the respective order. Upon receipt of the enable signal the client device transmits the printing data to the printer. Finally the printer informs the print server that the order has been completed.
However, this method has the disadvantage that the print server must transmit a message to the client device. In view of today's increasing safety requirements this is frequently problematic. The reason for this is that these days the client device or an intermediate device, as a rule, comprises a protection device such as a firewall. The firewall, however, restricts access to the client device from external devices. This means, of course, that the firewall also blocks the enable message actively sent by the print server.
According to the prior art this problem is known to be solved by explicitly disconnecting the protective application for all external devices such as a plurality of print servers, in order to allow the enable signal to be transmitted to the client device. Configuring a protective application in this way, is expensive however, in particular given she plurality of network devices to be disconnected which can quickly overburden a user. On the other hand, if a disconnecting error occurs, this may lead to unauthorised third parties gaining access to the client device.
It is therefore the object of the invention to provide a method for operating a network system which, in a simple way, permits reduction of the requirement for resources and the amount of maintenance involved whilst at the same time ensuring a low security risk.
According to the invention, this object is solved by a method for operating a network system according to claim 1. In particular the requirement according to the invention is solved by a method for operating a network system with at least one client device, at least one management device and at least one printing device. The method comprises the following steps:                providing a first order from the client device for execution by the at least one printing device,        storing the order in a memory device of the client device,        transmitting an order request from the client device to the management device, wherein the sequence of execution of orders is managed by the management device,        transmitting requests from the client device to the management device at first prescribable intervals of time to determine whether the printing device is available for executing the order from the client device, and        transmitting an enable signal from the client device in response to the request from the client device when the printing device is available for executing the order from the client device.        